The approaches described in this section are approaches that could be pursued, but not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated, it should not be assumed that any of the approaches described in this section qualify as prior art merely by virtue of their inclusion in this section.
The Extensible Markup Language (XML) is a standard for data and documents that has wide acceptance in the computer industry. Relational and object-relational database systems are enhanced to store and support query mechanisms for XML data.
It is important for such database systems to be able to execute an XQuery query or SQL query that embeds XML expressions, such as XPath and XQuery expressions. An expression is a component of a computer language statement that identifies a value or defines the computation of a value. Such a query received by the XML enhanced database systems maybe dynamically rewritten into an object-relational query that directly reference and access the underlying database objects (e.g. tables, columns, objects, object tables, LOBS) that store the XML data. This processing of rewriting is referred to herein as a relational rewrite.
Described herein are novel techniques for rewriting queries comprising expressions written in XPath or other XML language.